Hello Agung,
This information may be considered as proprietary or "know-how" by ferrous wire companies. No doubt it was obtained experimentally and at some cost. Thus they may not be willing to part with the information which also may be specific to the make, model, the reel or coil sizes, how the reels or coils are stacked, the geometry of and atmosphere circulation inside of the particular batch annealer in question. If you get no further response, I imagine this will fully tell the tale.
You may also wish to discuss this with EBNER Industrieofenbau Gesellschaft m.b.H.
Ruflinger Straße 111
A 4060 Leonding
Austria
www.ebner.cc/
Finally, you may wish to visit the Dusseldorf International Wire Show which runs from April 24-28.
www.mdna.com/
Kindest regards,
Peter J. Stewart-Hay
Principal
Stewart-Hay Associates
www.Stewart-Hay.com